Tech & Product

Metallized Carbon Corporation Announces Mechanical Seal Primary Rings for Sealing Refrigerants and Other Low Viscosity Liquids

April 25, 2014

Metcar Grade M-444 offers self-polishing characteristics and dimensional stability

Metallized Carbon Corporation announces the availability of mechanical seal primary rings for sealing refrigerants and other low viscosity liquids. Designing mechanical seals for sealing refrigerants and other low viscosity liquids has been a difficult problem for seal manufactures for many years. It has now been established that mechanical seals with antimony impregnated, carbon-graphite primary rings and solid silicon carbide counter face rings can solve this problem.

Low viscosity liquids such as Freon refrigerants, liquid oxygen, liquid carbon dioxide, propane, ethylene, and acetone are now being successfully sealed using mechanical seals with Metcar Grade M-444, antimony impregnated, carbon-graphite primary seal rings.

Low viscosity liquids are difficult for mechanical seals because the hydrodynamic film that they create between the two rubbing seal faces is extremely thin. In order for this extremely thin hydrodynamic film to lubricate the two sealing faces, the seal faces must stay highly polished and they must run in very close proximity to each other. It is the self-polishing characteristic of the M-444, antimony impregnated, carbon-graphite material and the high dimensional stability of both solid silicon carbide and antimony impregnated carbon-graphite that enables these two materials to run in the required close proximity. Ordinary mechanical seals with resin impregnated, carbon-graphite primary rings do not have the self-polishing characteristic or the dimensional stability that is required for sealing these low viscosity liquids.

For additional information on mechanical seal primary ring materials for other difficult sealing applications, call 914-941-3738 and visit

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